Spectrophotometry of chromium salt

  1. 1. The problem statement, all variables and given/known data
    Why is 575 nm wavelength used in spectrophotometry of Potassium dioxalatodiaquochromate (III) dihydrate?

    2. Relevant equations

    3. The attempt at a solution
    Cannot find discrete reasoning!
  2. jcsd
  3. Borek

    Staff: Mentor

    I would start searching for the full absorption spectrum.
  4. Yes I did search for it and found a page --> http://science.herograw.net/chem333l/CHEM333L-UV_Vis.pdf . But their reasoning is purely based on errors on absorption that were determined when using a variety of wavelengths. But I was wondering if there was a theoretical reason somehow including the concept complementary colors?
  5. Borek

    Staff: Mentor

    I have never heard about using complementary colors for the wavelength selection. If you have a single substance you will usually select wavelength for which the absorption coefficient is the highest, as this gives the best sensitivity. If there are interfering substances, you will select wavelengths for which differences in absorption coefficients between your substance and the impurities are the highest.
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